Process of making indoxyl.



in No. 731,385.

UNITED STATS Patented June 16, 1903.

ATENT PAUL ERWIN OBERREIT, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY,

ASSIGNOR TO BADISOHE ANILIN UND SODA FABRIK, OF LUDWIGS- HAFEN-ON IHE-RHINE, BAVARIA, GERMANY, A CORPORATION.

SPECIFICATION forming part of Letters Patent No. 731,385, dated June 16, 1903. Application filed March 31, 1903. Serial No. 150,465. (No specimens.)

I ing taken to exclude Water, as far as possible, from the materials, both before and during mixing,) and the mixture is then heated. This grinding is, however, a tedious, expensive, and at times uncertain operation, so

.20 that attempts have been made to dispense with it by mixing the materials in aqueous solution and evaporating 0d the water. Under these circumstances, however, a partial decomposition of the phenyl-glycin-orthocarboxylic acid takes place, so that but little indoxyl is obtained from the melt.

I have discovered that an aqueous solution of phenylglycin ortho carboxylic acid and caustic alkali can advantageously be em- 0 ployed for the production of indoxylic acid and indoxyl if the mixture be heated in a vacuum. The water evaporates without decomposition of the glycin salt taking place, and condensation to indoxylic acid or indoxyl 5 is smoothly effected.

The following examples will serve to illustrate the nature of my invention, which, however, is not confined to these examples. The parts are by weight.

Example 1: Mix a solution of twenty-four (24) parts of phenyl-glycin-ortho-carboxylic acid disodium salt in one hundred (100) parts of Water with one hundred and fifty (150) parts of caustic-soda lye, containing about thirty-five per cent. NaOH, and evaporate the mixture in vacuo. Finally heat the whole to a temperature of over two hundred degrees centigrade, (200 C.)

Example 2: Mix into a paste'one hundred and ninety-five (195) parts of phenyl-glycinortho-carboxylic acid and four hundred (400) parts of Water. To this add gradually a mixture of thirteen hundred (1,300) parts of canstic-potash lye, containing about twenty-eight (28) per cent. KOH, and eight hundred and fifty (850) parts of caustic-soda lye, containing about twenty-four (24:) per cent. NaOI-I. Evaporate the whole in a vacuum and finally heat the mass, while stirring, to a temperature of about two hundred and fifty degrees centigrade (250 0.) until indoxyl practically ceases to be formed.

I claim- I The process for the production of indoxylic acid and. indoxyl by mixing phenyl-glycinortho-carboxylic acid with caustic alkali in presence of Water and heating the mixture in a vacuum until the desired condensation has been efiected.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

PAUL ERWIN OBERREIT.

Witnesses:

JOHN L. HEINKE, JACOB ADRIAN. 

